1. Field of the Invention
The present invention deals with the coating of glass surfaces, especially glass bottles with a duroplastic polyisocyanate-polyol containing paste.
2. Description of the Prior Art
The coating of glass surfaces, especially glass bottles, with a very adhesive uniform and transparent layer of plastic, makes bottles extremely safe when they are used for carbonated beverages, such as beer, cola drinks, mineral water, fruit-juice drinks, etc., and in the case of returnable bottles, prolongs their usage. Because of blows and bumps, but also through the effect of heating in sunlight or by other heat sources, there have been in the past frequent explosions of unprotected bottles which have caused injuries of varying severity, especially eye injuries in humans.
Some of the previously known coatings for this purpose have the disadvantage that after repeated cleaning, the coating layer starts to cloud which, in the case of thermoplastic materials, may possibly be the result of an after crystallization effect of the plastic. Such bottles optically also make a negative impression and from the point of view of sales psychology, are also undesirable. The disadvantage of duroplastic, ether group-containing synthetic coatings is the rather low tearing strength and the oxidative susceptibility which results in an embrittlement of the protective layer, and thus, especially in the case of returnable bottles, after some time no longer guarantees protection against shattering.